I have a D-Link DI-624 router and I understand that I can convert this router to a repeater using on line software thus allowing me to extend a wireless signal from up to a 1/4 mile away. Your help would be appreciated
I assume you're referring to third-party firmware. To my knowledge, the DI-624 does NOT support any of the well-known third party firmwares, be it dd-wrt, tomato (which doesn't support repeating anyway), or openwrt. So as far as repeating w/ the DI-624, you're up the creek.
And btw, no consumer-grade router (stock or third-party firmware) is going to get you a signal up to 1/4 mile. No how, no way. Not without help from something like a cantenna or similar device. With stock antenna, you'd be lucky to get 100-150 ft.