where can i find PDF in the net that are free?

I'm not sure what you mean. PDF files open with pdf software which is generally free. Just do a search and you can probably find some. If that is what you mean. Most computers come with it.

If you're talking about only reading pdf files, Adobe's reader is free, and it lets you save the file, or keep it on your desktop if you need to read it and study it. If you plan on making pdf files though, Adobe's pdf maker costs a fine chunk of change lol. I use Primo pdf from primopdf.com. It's great, plus it's free to download and use. Primo's lets you create pdf files fairly easily. I have Adobe installed on my computer because that's what most websites use, but if I'm actually making a file myself, I use Primo PDF. Note: Anything pdf file created with Primo can still be read by Adobe.