Is this correct?

Bu çok güzel bir ev.  = This is a very nice/pretty house. 

Bu çok güzel bir evdi.  =  This was a very nice/pretty house. 

Also, I´m  wondering about this:

Bu çok güzel bir evi. <<  is this a correct way to write it or no?  or do you use ´i´ for ´the house´ instead of ´a house´?  

and would someone write:  Bu çok güzel bir evidi?

I don´t think you can use "i" for "the" in this sentence, only as a direct object of a verb.

In Enlish, you wouldn´t say: "This is the very nice house" either, you´d use "a", so I think your first translation is the best. If you want to say "The house is nice", you´d just skip "bir" and say  "Bu ev çok güzel." or "Ev çok güzel."

Using a verb would these sentences be correct?   I hope.

This was the house i wanted.
 
Bu evdiyi istedim.

This is the house I wanted. 
 
Bu evi istedim.

"Bu evi istedim" is correct, the other one isn´t (as far as I can tell, but you know I´m just learning too .

To say this was the house I wanted you´d say: Bu istediðim evdi.

Thank you very much both of your explanations and corrections.  Hmm, the ´-dik´ participle I havent studied any of that yet.  But, I´m catching on a bit 

Well, are these correct?

I am in the house.  = Ben evdeyim.
I was in the house. = Ben evdeydim.
I am on the street. = Ben caddedeyim.
I was on the street. = Ben caddedeydim.

Yes.

Correct.

cool thanks again. 

?  would it be correct to say it this way also:  I am in the house =  Evde oluyorum or Evde olurum.

                                                                        I was in the house  = Evde oldum or Evde olurdum.

if it is correct to say it that way, what would be the difference than the other way?

Correct, but changes the meaning.

"Evde oluyorum" is like "I am at home(generally)". It doesn´t mean that you are at home now but you usually stay at home.

"Evde olurum" is the same as above, but it can be also used for future; I think you can also say in English "I am at home tomorrow".

Evde oldum , no there is nothing like that (I don´t know why )

"Evde olurdum" is "I used to be at home".