Kiwi Farms

This year has been mostly been me fucking up my body with injuries this summer i fractured my arm by running into a tree with a bike when out in the fields.
And while ago i twisted my ankle, twice!
I wont be able to use the foot properly for at least 6 months apparently.

At the same time i kinda self dieted by minimizing my food intake to 2 meals small launches and lost 15 kilos since that summer.
If anyone wants me to write down my eating schedule just ask.

In any case i am now lighter and feel like i want to start doing some upper body exercises.(yes my arm is ok now)
Never really attempted exercise in my life and i don't know how to start.
I have a 2 old rubber dumbbells at home that are 1kg each.
How much is one supposed to do as a starter?