have been a reseller for a while and having the urge to get a dedicated server, but was wondering what do I need to know to manage it? the most I know so far is installation of some application.

Two things you should know:

1. How to search WHT because there have already been 298598275 of these posts, read those instead of asking us to post again and again and again and again.

2. Most people charge money for their time to assist people on managing servers - then again WHT is full of people wanting something for nothing - so I guess you fit in with the group.

That being said, maybe you should look into managed services, or Semi-Managed and read some Unix howto's. RackShack has a HOWTO forum that could help you out.

One word:

Linux :D