Head gasket

I'm not a mechanic.How hard is it to replace the head gasket?What should
I look out for?Anything I should do while the head is off? How long
should it take?how do I make sure the head is good?Valves?Where should I
get parts for it is there aftermarket?It is a small combustion gas leak
into the glycol so far how do I make sure the motor deck (where the head
sits) is OK?Sorry for all the ?s but both our vehicles are down with
this problem and we can't afford to have a shop repair them @ $1100-1300
each.please email me at (E-Mail Removed)