Dumb question about calorie deficits and weight loss

[nothing2lose]

Thanks

Exercise is totally foreign to me (which explains a lot ) i have never been to a gym You'll have to be patient with me!

So, I am 40, which makes my MHR 180.

60 per cent is 108
70 per cent is 126

I guess I will aim for 70 per cent at this stage. I have a Polar heart rate monitor which I am trying to set up. It has a 'zone' you program into it as a target. I guess I will set the 108 as the low and 126 as the high for now. Is this
right?????

Also, i am not likely to join a gym in the immediate future. I have an exercise bike. I also have Wii fit. DP has a weight bench thingo but it seems a bit daunting at this stage.

Do you think I should start with the bike, walking and Wii???? What exactly is resistance training??

Like i said, words like pump, spin, cardio, etc are foreign

Eta: I thought I should aim to burn 500cals a day through exercise. Thoughts?
What about eating back your calories??? Do you do this? (lol By 'you' I mean anyone out there!)