I'm using beta version 3b.
I can't seem to get the word wrap feature to work.

I have "word wrap" on the EDIT drop down menu checked (selected) and I have "word wrap at 76 lines" checked in the Options->Editor Options box.

Typing past column 76 doesn't cause a carrage return to next line.

What did I miss?

It the version 2.51 Word Wrap was been GWD Text Editor global property and now it is a document property. You can have word wrap turned on in the one document and turned off in the another.
You probably select Word Wrap in the one document, and switch to the another document.

I am new to this program as a result of changes made to Wordpad in Win2k. Previously, I was able to create files with lines of infinite length. That is, at least I never discovered a limit and many lines are near 4,000 characters long. Can this program support this? If so, what settings are necessary?

GWD Text Editor line limit is 4000 characters, and cannot be increased.