91 Aerostar starter

hi, i just joined this forum.
i hope someone can help.
i live in Edmonton Canada, so it's been very cold here.
i tried starting my 91 Aerostar Thursday morning.
it turned over but wouldn't fire, after a couple of tries, the battery
was getting weak.
i tried to get it jumped, it almost started, but after a few tries nothing.
not a peep.
the running lights work, the radio works, i can hear the fuel pump when
i turn the key halfway.

i took the battery inside last night, thinking it was frozen.
i tried again this morning, but nothing.
i realized my block heater wasn't working, so i went and bought
one of those magnetic types and attached to my oil pan.
after several hours, still nothing.
someone has suggested the starter or solenoid.
i am totally ignorant when it comes to vehicle mechanics, so
any help as greatly appreciated.

thanks