Well, youre certainly starting off on the right track, I dont mean the hardware so much, referring to the beans ;). Before anything else, youve got to have quality freshly roasted coffee and you will certainly have that with Cosmorex Coffee.
The little SB Ristretto coupled with the SB EMO480 Grinder should be capable of producing good results with a standard basket (the receptacle that fits inside the Filter Handle or better known as a PortaFilter). Standard baskets are constructed from a single piece of stainless steel in Double and Single coffee dose sizes and have heaps of tiny little perforated holes in the bottom through which the coffee liquor is pushed (under pressure from the Pump).
The baskets that would have come with your Ristretto are known as Pressurised or Double-Walled baskets. If you tip them upside down youll notice that they will have a single small hole in the outer shell, on the bottom, through which the coffee is forced under pressure so as to emulsify the oils and other soluble components in the coffee, to give the impression of "Crema". Unfortunately, this stuff is NOT real crema, just a poor facsimile thereof that can be created from coffee no matter how old and stale it is, typically bought from supermarkets in Brick form. To have any chance at all of getting the best out of those lovely beans youve bought though, you really do need to try and grab some standard baskets.
These can be bought from Krupps suppliers, as per info contained in this thread, or from Breville service agents as "Part No. ESP4/ 1-2 Cup Filter". The Breville basket obviously fits perfectly into Breville PortaFilters but from what Ive read in other threads, it also fits pretty well into the lower-end SB machines too. Apparently, the Krupps baskets can be a bit loose in some PFs where-as the Breville ones are a nice tight fit. Lots of people use the Krupps baskets though and get good results with them.
Until such time as you get the new standard basket(s), you should be able to get reasonable results from your existing Pressurised ones using the Cosmorex coffee. You just need to set your grinder to a slightly more coarse setting than that usually used for espresso, somewhere close to that of Drip Filter Coffee will be close. Only use the Double basket when first starting off as the Single can be quite difficult to come to grips with until you get the variables of the correct technique under control, so leave it in the box for now.
Turn your machine on and allow time for it to warm up properly, about 1/2 an hour or so, with the PF lightly nipped in to the Group. All metal parts that come into contact with the coffee must be allowed to come up to normal operating temperature before attempting to pull a shot. Trying to do so before this has occurred will result in quite sour and unpleasant espresso pours :P.
OK, with the machine now up to temperature you can get started. Measure about 2 1/2 scoops/tablespoons of coffee beans into the grinder hopper and grind this at the setting mentioned above, either direct into the PF Basket or into a suitable small container and then transfer this into the PF Basket. Overfill the basket slightly so that you have a small mound of coffee above the lip of the basket. Tap the PF lightly on the bench a couple of times to settle the grounds a bit, level off with the side of your finger or the back of a knife blade and then, using the plastic Tamper supplied with the machine, lightly tamp the coffee down so that the surface is about 4-6mm below the lip of the basket, nice and level and flat right to the edges of the basket. Lock the PF into the Group so that it is firmly locked in as far as it will go and then hit the Brew Switch on the machine (with a cup or glass under the spouts) ;).
In the ideal world, youre aiming to produce an espresso volume of about 60mm in 25-30 seconds after hitting the switch. If your pour is too fast then you will need to grind a little finer, or coarser if the pour is too slow. That is it, in a nutshell. When you get the standard basket(s), you will need to pay a lot more attention to dosing the basket with the same amount of coffee consistently, will also be advisable to get yourself a decent, correctly sized Tamper so that you can do this consistently such that the only variable that will need to be changed, is the grind setting. Takes a lot of practice to get the technique sorted out but there are lots of people here at CoffeeSnobs only too happy to help you out as best we can, so dont be frightened to ask questions..... Most of us started right where you are now at some point in the past.
Anyway mate, hope thats enough to help you get started. All the best for now and Happy Brewing...... :)