Im on Mac, but it did that to my phone the first time. what you do is keep it plugged into your pc until itunes re-reconizes it and connects to itunes to verify the ipsw
once it does that you should get a notification in itunes and then it will prompt you to make a name for the phone, auto sync and another option which escapes memory right now.
once you do that the iphone should say "please wait for activation" give it about 2-3 mins. and you should be good.
listen this might sound weird or like im being a arse but it's not and im not either but hear me out
My first JB'n took me like 2-3 tries, and all I did was throw my phone back into DFU(sp? wrong abbreviation?) Mode, re-ran pwnagetool, recreated another custom ipsw and re-did the whole thing till it took.
You are going to have to keep working with it till it takes, you gotta understand that what you are doing is going against the accepted programming of the phone its going to take a few attempts or tries before it takes.
so just show patients and dont give up, if that doesnt work then come back here and i'll attempt to assist you more. but also you are going to have to use the search feature on here as well as in google to find fix-actions because the issue's I have had with JB'n all had been covered before either on this forum or on a blog, website or another forum.
You should just be able to insert your SIM card, and allow the phone to do it's own workings and it should activate on it's own without additional computer or user work. Atleast thats how it works on the Mac and my phone 😀
(just jeffing with you on this) but suggestion: Buy a Mac, Download Pwnage Tool and you wont have issues .... ??? lol