I would humbly suggest that you try out the stuff. Meaning write a small script that will use .= because thats what I did, and right after that, I tried it with a =. :). It gave me some error, but heck, thats okay. Once you do that, Then, read up the Perl Documentation, or do a google search as that will tell you why that stuff is there. Don't be afraid to try out stuff. Thats the best part of scripting...Have fun buddy :)
I would also sincerely suggest that you look up perl documentation. You'll come across some real eye openers. One of the strengths of this beautiful language, is its awesome documentation. Use it, you'll thank yourself later.
Perlpetually Indebted To PerlMonks
print "Awesome Books";
is a boon for Windows.