Bottom bracket lock ring loose - how should I tighten it I can feel so laterial play when grab hold of the crank arms then wiggle it side to side. I discovered the lock ring  was very loose. So much so i could turn it with my fingers without any effort.

When I tightened the lock ring just by hand, the play went away. I loosened it then it came back.

Does this mean my bb is unscrewing itself from the frame and i need to tighten it up? 

Is this a job for a  newbie home mechanic to attempt?
Loosen the lock ring, then tighten the bottom bracket cup until the play goes away and the crank moves smoothly. Then hold the bottom bracket cup in place and tighten the lock ring. 

There are special spanners you can buy for this or you can use an adjustable spanner to move the bottom bracket cup and a screwdriver tapped gently with a hammer to tighten the lock ring. You may have to improvise further with your choice of tools. You may also need an assistant.

A newbie mechanic should have no problems doing this. If you don't try you won't learn.