vasilis13! there are many choices for you. Most of the free web sites put their advertisements on your web pages. .. anyway...
Geocities
Http://www.Geocities.com .. this has one of the most friendly file managers available for beginners.. now i don't know U r a beginner or...
Freeservers
Http://www.Freeservers.com ... I am using it for more than 4 years... It is one of the best free web space providers... they used to give away 20mb.. but now they offer 12mb.... that is enough for a normal site...
Someone mentioned Bravepages too... its good.. but in my experience... its slow... I don't know the exact reason... but for me its always slow..
One more thing... you can also use short URLs from sites like CJB.net...
For example if you get your free space from Geocities... your URL will be something like
http://www.geocities.com/vasilis13 .... then you can go to
Http://www.CJB.net and signup for a free short URL ... and get vasilis.cjb.net ... or any choice you like.. it will forward this URL to your actual space........... and will be easy to remember........

If you need any further help, please feel free to ask!
Best of Luck!