I replaced my battery in my car and there is still no power at all

A new battery from the store is sold with no charge in it. It will need charging before it is used.

If a jumpstart dosn't work, then there are high power fuses, called fusable links, that may be blown.

Along the positive lead, either at the battery connector, or sometimes at the alternator connector, there is a short wire about 6 inches, it will be the end of a longer red wire leading to the battery terminal or alternator.
It looks like a regular wire, but with a connector attached about six inches along. If this wire stretches and breaks, or has burn marks, or is simply a strip of carbon, then this is the problem, and needs to be replaced.

Otherwise there is often a fusebox relay box under the hood, (in addition to the interior fusebox). Check the fuses in there.

What kind of car do you have. it sounds like you blown the main fuse or have a dead starter