What strength machines should a gym newbie use?

I started working out at home in Feb I was 230ish at the time. I've currently weight 190, I'm 5'2" and 35 year old female. I've recently gained access to a gym for free so I plan on using it but I don't have much experience with gym equipment and there is no one at this gym to advise me so I'm wondering what machines I should use. My goal is to be able to do a full sit-up, I can barely get my shoulders off the mat now and to be able to do full push-ups I can do about 20 modified now. Up till now my workout schedule has been to jog on a manual treadmill and to do p90 (1 not x) with 5lbs dumbbells which are getting too light for me. I'm thinking of doing the following as I quickly get bored.

Sun- stationary bicycle 1hr-2hr
Mon- p90 with 7.5lbs dumbbells and 1hr treadmill
Tue- off
Wed- strength machines, I need help here not sure which ones, and 1hr treadmill
Thur- off
Fri- repeat (mon)
Sat- elipitical 1hr-2hr

Not having much experience in strength training I'm not sure if this is right. I'd like to lose about 60 more pounds and build some muscle. I'm okay diet wise so I don't need advise there. If anyone could give me advise or suggestions I would greatly appreciate it.