Looks like it's a cone type hub, which you can adjust if you have cone spanners - 13,14,15,16 mm in size (15/16 for rears) but you do need the thin cone spanners, or someone who is handy. They aren't difficult to adjust, but take care and time to do it, if you are not mechanically minded, then the local bike shop is best ! You might get away with adjusting from the non-freewheel side if lucky ! Freewheel side is more tricky and depends if you have a free hub or the older screw in freewheel (i.e. slot in sprockets with a lock ring(freehub), or a whole gear system that's screwed on, although sprockets can be changed like freehubs)...
If you know what you are doing, then it's a simple job, but if not, do find a friendly local bike shop.