Im confused here, getting my information from various searches on google I am haveing a hard time understanding certian aspects of DNS and woundering if someone can clerify:

Say I want to set up my own personal web space but host it on my own computer. I go to a registrar and purchase a domain name for a 1 year period. But they don't give me a DNS server, so Im left with a domain name, its parked and I have no DNS. I need the DNS to atach my ip to my domain name corect? Now lets say my ip is also dynamic. If I went to a web hosting company I could pay them to host it and theyd give me a DNS server address to use. But I want to host it myself. So I download a web server such as Apache for example. How do I get a DNS now? I discovered a service DNS2GO offered by www.deerfield.com and they say this

The DNS2Go service associates a static real name to any IP address, from dialup to DSL and cable. Deerfield.com provides dozens of top-level domains to choose from, making names truly unique and personal.
So I purchase the DNS2Go 1-Year License Single Domain for $19.95

Here is where Im confused.

1) Without useing DNS2GO wanting to host my self but looking for other prices from other places, where else can I get a DNS server without the extra cost of a host?

2) Reading about DNS2GO you need a download if youve got a Dynamic IP, are there other freeware alternitives, seeing I dont know what the download does?

3) If I have a Relitivly static IP gathered from a DHCP server is this step of DNS realy nessisary?