Need more info.

Is it transparent,semi-transparent,semi-solid,or a solid stain?It will say on the can.

It should be pretty easy to change from red to brown. But as RET said you need to know what you used on it last year.

I think I used a solid stain. Thanks.

If it is a solid stain it will be like paint,a transparent stain is like what cabinets or bath fixtures,wooden desks in m enards or h ome depot or furniture stores would be.

If the case is that your swing set is a solid stain then just get a different color of solid stain and apply over it,as long as the stuff on it isnt peeling or chipped away.Solid stain does not need to be primed it is already a sealer just put color you want changed to right on it.

Thank you retisin, I'll give it a try. Thanks for your time.