So i run through a router hooked up to my mums computer. I want to forward these ports so i can host a LFS server but everytime i got to forward the port, the browser locks up and gets a non responding deal going on. The router is a D-Link 540t, any help would be really appreciated!

Have you tried a different browser? Each router will be different and its impossible to support every single one, but the LFS Manual (Wiki) should help you with the ports you need opened. (link at the top of every forum page).

After a quick google search, ive not found anything exactly for that router, but surely if you look, you will find a manual of sorts or a guide somewhere. In my experience (limited) its the Firewall Rules and Ports options that are needed and most important.

But first, we have to get you past your browser issues, which cannot be done, unless we know what you are using

Go with Stoney's advice first of all and it's possibly a browser bug. If it still happens it could mean that it's your router accepting the change and then restarting without commiting the change. If it's not commiting the change then I'd suggest looking at firmware updates for the router next.