OK what are you trying to do? what type(s) of music do you want to create? what other equipment do you have, that can be used with the rack?
I'll say this on the assumption that you have done near 0 research - return the case if you can and get a bigger one - tiptop mantis or doepfer lc9 are good starter cases - because that way you won't be buying another one in 3-6 months - better to start with a big case and fewer modules than a nearly full small case!
often recommended starting modules are: a sound source, a sound modifier, a modulation source, a way to play and a way to listen - including/plus a quad cascading vca (which may be your way to listen) and a utility starter set of something like links, kinks and shades - I would try to follow this more closely
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities