[Q] HTC ONE M8 Sprint topic

Hello Good and Helping members and mods.
Let me tell the whole strory before i ask any help.
I buy the HTC ONE M8 Sprint phone in ebay. The member who sale, he tell its unlocked and bla bla bla..... Ok, i buy, wait 2month for the phone, because i am in Latvia. I got the phone, i turn on the device, everything great, i do all the stuff, trought WIFI, everything good, device is working and soound working. Then i insert the SIM card, then the trouble begin.
Its showing the device dont regonize the SIM card, and cant use in 4G aka LTE, ok, i switch to the GSM, same s*it..... Ok, i start searching the internet, found website ( i will not post, to i dont advirtise anything ) they send me some unlock code..... But where should i put it ? I dont see such a thing to put the CODE.
I need a member or mod, or some guy who know every step to unlock my phone, maybe the GUY can contact me trought my email - egils.gridins@gmail.com tell me everything, i can call to skype and he teach me steb by step, or use some TeamViewer to he can unlock the phone ?
I try to root from this forum, i cant, or i am to dumb, or there is to much smart words in those instcructions?

Please help me to unlock the phone... I try already like 1 month, nothing help.
Sry for my bad English i am from Latvia.....

Best Regards, Egils Gridins