The correct usage for the word "since"

can anyone tell me the correct usage for the word since. i have two.
ponieważ
odkąd
both mean since, but in what context. by the reading on these words i suspect it is odkąd.
but i stand corrected

chaza

It should be odkąd - when you are talking about the time. fi:
Since he came so much has happaned (...)
Odkąd przyjechałem tyle się wydarzyło...

And in places where you could change it to because - it can be ponieważ.
Since you asked politely then I will tell you (...)
Ponieważ grzecznie spytałeś powiem ci...

At least that's how I see it, might be wrong though ; o

You can also use 'od' in that context in sentences like:

I've been working on it since yesterday.
Pracuję nad tym od wczoraj.

The use of od/odkąd depends on how you express the moment in time something has been (being) done since. If you use a noun then in Polish you use 'od' but if you use some descriptive expression (another setence) then in polish it'd be 'odkąd'. e.g.:

since yesterday - od wczoraj
since last Summer - od zeszłego lata

but:

since he came - odkąd przyjechał
since the bought the new car - odkąd kupił sobie ten nowy samochód...

odkąd = od kiedy

e.g.:

since I met you - od kiedy cię poznałem


Yes. Also you can use 'bo', 'dlatego, że' etc.

Cinek

oh that has put the brakes on a bit, i understand bo to mean'because', dlatego to mean ' for that' and zę to mean 'that'. have i misunderstood.

chaza

No, just the meaning may depend on the context and there's no one to one translation for those words that always works.

Cinek