How do I get this slot ready for planting?

It's been unused/ untouched since at least the fall 2014.
There are mole holes and also a bit of vermin compost making last summer and fall.
It's about 4x4 meters.
I really have no idea on what to do. Or even if there is enough time.
Could I just do a piece of it? I won't be planting much this year, as I want to start small.

 

I'm in South Germany. Now it's sunny in the mornings and afternoons. In spring and summer only has shade in end of the afternoon.
I was thinking about potatoes, bell peppers, tomatoes and lettuces. But the lettuces might be in pots, at least the first ones.
I'm not sure about the peppers and tomatoes because I don't think I be able to buy a green house this year, and we have a couple of big storms in the summer with winds of 60-70 km/h.

 

Should I just dig ant trow out the top few centimeters? And then buy new soil for the area needed?
Or can I still save it?
Is it possible to just get small square ready?

edit:
The corner with the tree is facing south, and the corner with the ruined composter is east.
The shade comes from NE (bushes) and NW (play house). There is also some shade SW made by trees, but it's mostly on the borders.

 

Is a month before spring enough?
Can I just prepare a small square? Or will the weeds spread?
What tools are best to work with, for newbies? I have some in our shed, left by previous owners.
I really have no idea what I'm doing

 

As John has said, just dig it over. I would use a garden fork for this, push it in with your foot, lift up soil and turn it over as you put the soil down. Personally, I would bash it once or twice with the back of the fork just to break it up a little, then leave it to the frost. If you see any roots remove them at the same time. Don't use a spade for this as you will cut any existing roots in half. Do the whole plot.

Once spring arrives and you know how much ground you will need for planting, you can cover the rest to prevent weed growth.

But get it turned over, nothing fancy...let the frost work it's magic.

Steve...

 

agreed! keep us updated with pictures please

 

Is 4-6 weeks enough to the frost to work? Because that's how much there is left.
And the soil is different is different places.
Thers some bits with dark brown and light brown. And some just look like dried mud.
Should I mix it all together, or will it be ok after frosting?

 

Turn over, leave till spring...it'll be fine.

Steve...

 

Taken today
The bit that I have worked it's just 1x1.2 meters.
I need 1.5 x 1.5 for the green house.
The soil looks (and feels) heavy.

I want to put potatoes and will be transferring leeks into it. What should I add?

 

Hi @cathymoon,

You are doing a grand job , I'd add some well rotted farmyard manure (horse muck or pig poop is what I generally use)

 

I might have some compost made of grass and leaves. But it won't be much, my upstairs neighbour destroyed our two composters and spreaded the first one on the grass garden. He said he wants to use that compost, I'm not sure it it's still usable as it already has all sort of weeds growing.
I've been digging about a foot deep. I hope that's enough. But it's taking a long time to do. That bit took nearly 5 hours. There are so many weeds in it.

When should I start the potatoes? I need at least a week until I can build the greenhouse. Should the potatoes be inside or outside? It will only be heated by the sun (it will be quite hot in August, but that's it).