You are in luck: the internet is densely populated with philosophical texts. Good places to start are:
www.gutenberg.org (also, they have a small set of recommendations in their 'philosophy bookshelf' but it represents only the tip of an iceberg!)
and Google books has hundreds of pdf scans of old volumes.
Now, there are three problems with these sites: for the most part, they present texts without commentary or explanation; often they use old editions or translations (because they are out of copyright); and finally, for the same reason, they tend to emphasize philosophy from times past. Recent philosophy is more difficult to come by, but not impossible. Certainly useful introductions can be found at the Internet or Stanford Encyclopedias; also, university teachers often put their lecture notes up on the web.