I have a 1995 f150 with the 5.0 and I was wondering how I could get more power for pulling

Easiest upgrade to do would be a performance module. It's showing roughly a 15hp gain for your truck. Although I'm always a bit skeptical on these hp figures. Maybe someone can give you some feedback that has used one. You may gain another 5-10 hp with an aftermarket intake and exhaust.

How do you install it and how much does it cost

How much more pulling (in lbs) do you need? The rating on the sticker inside the door should indicate the limits for your vehicle for how it is equipped. I would not exceed it greatly. There is more to pulling than just an engine. Cooling, braking, and transmission has to be taken into consideration.

It has 33s and a f250 transmission it's just the motor that's 150

I have heard those modules don't do much and you may never pass smog check with one. I would look at smog legal exhaust and intake mods. There are tons of parts for the Ford 5.0. I suspect the 33's are really dragging your truck down. I would look at re-gearing the truck.