Whats a correct principal part of a verb , and infinitive part of a verb?

Question

Verbs have three principal parts, although some dictionaries and grammars list four. So I'll show you four in case that's what you are supposed to know.

For "regular" verbs:
Base form = walk
Simple past = walked
Past participle = walked
Present participle = walking

For "irregular" verbs:
Base = go
Simple past = went
Past participle = gone
Present participle = going

More information is here: http://grammar.ccc.commnet.edu/grammar/verbs.htm

The infinitive is simply the base form with the word "to" in front of it:

to walk
to go
etc.

=)