The subcategorization frame gives you information about the syntactic category a verb (or, predicate in general) combines with. This information has to be found verb by verb, i.e. it is idiosynchratic.
Take the following verb:
Let's focus on the complements this verb can take. Among all the categories there are (NP, AP, VP, IP, CP, AdvP...), the verb like only wants a proper subset of the set of all syntactic categories after it. This is why we talk of selection or, more precisely, c-selection (c for category). Imagine a ball where it is ladies' choice: the ladies walk around and choose the guy they want to dance with (and by doing so they dismiss the guys they don't want to dance with). In a similar vein, our verbs are discriminating and don't just take everyone. What is ladies' choice for the ladies, c-selection is for the verbs. The verb goes through various categories and says: "You, I love and combine with." To those categories the verb doesn't like, it says: "You, I don't love and don't combine with." Through testing the various syntactic categories this verb can be followed by, we get to know its c-selection:
1.1) John likes [_NP the car] 1.2) John likes [_CP to go out in the afternoon] 1.3) *John likes [_AdvP quickly] and so on...
This way we get to know that like has at least the following subcategorization frames, i.e. c-selection properties:
2.1) like: V, [---NP] 2.2) like: V, [---CP]
The V after like just gives you the syntactic category the word belongs to. The interesting part is in square brackets, which is the subcategorization frame (you don't need to specify the categories the verb does not c-select).
For intransitive verbs which are not subcategorized for a complement, we just leave the square brackets blank:
3) snore: V, [--- ]
For ditransitive verbs which are subcategorized for two complements, we write
4.1) send: V, [---NP, PP] 4.2) send: V, [---NP, NP]
The first frame corresponds to expressions like send the invitation to John and the latter frame corresponds to expressions like send John the invitation.
Usually, the subcategorization frame displays information about complements (i.e. the direct and the indirect object) only, since there is a seperate proviso for the subject, namely the Extended Projection Principle (EPP).