You said "in wordpress" if your blog is hosted free in wordpress.com, you can't place adsense or any other ads.
If you have your own hosting account go to
http://wordpress.org, they have the support that you need.
For adsense use this plug in
http://wordpress.org/extend/plugins/adsense-manager.
Website links of those who leave comments by default have nofollow tag, use this plugin if you want to remove them (but beware of spammers) - dofollow tag -
http://wordpress.org/extend/plugins/sem-dofollow/
Hope it helps
