hey guys i need some help, first off i'm completely new to this, so bear with me please.
I have a netgear wnr3500l

I wanted to install a tomato build made specifically for that model router.
here is the tomato build name: tomato-K26USB-1.28.7476MIPSR2-Toastman-RT-Ext

from what i was reading i had to first install dd-wrt, and from there i had to change the tomato extension from .trx to .bin. first thing i did was to change the extension, afterwards i installed dd-wrt. i used a version that was linked on a forum site where someone was asking how to install tomato.

the dd-wrt version i used was this:
dd-wrt.v24-13309_NEWD-2_K2.6_mini-WNR3500L

when i installed dd-wrt everything went fine, i did have to close browser and open it again due to screen going blank every time i tried to save a setting.
after that i upgraded firmware to the tomato build mentioned above.

as soon as i did that the router stopped responding and i only get orange lights. it sends a signal but you cant connect to it, and connecting through lan port gives me nothing.
i read a forumtopic on testignto see if router was bricked. 

i connected to the lan port, set my ip the same as the router and pinged it. it said something about time out a few times, and when i turned the router off then back on i was getting a ttl of 100. for a few times then i was getting time out message again

If i understood correctly what i read, that means that  i have to flash dd-wrt trough tftp.
here is the thing i have no idea how to do it, i am currently using a windows 7 computer which apparently gives some trouble, but i also have a windows xp computer that i can do it from.

can you either tell give me an extremely noob friendly step by step one how to fix this router, or link me to such a step by step.
any help is appreciated