Greetings!
I shot my first footage in "16:9" the other day, actually I shot it in 4:3 with 16/9 Guidelines. since i've been told that its possible to add somekind of mask and export it like 16/9.

Now you can see my problem, I have no idea to do this..
I've looked everywhere and tried varrious stuff

I know that I imported it in 4/3 (its 4:3 footage, but I made my composition and stuff for 16/9 with those guidelines).

hope someone knows what to do,

thanks!

You can simply create a 16:9 project in Premiere and the import the footage in it. When you create a project click on the custom settings, select Editing Mode => Desktop, Frame size 720x405 (16x9), pixel ratio D1/DV (0.9) and you are all set.
Now you can import you footage and also move it vertically in order to reframe your shots if you need. Since you still have the full frame you ca take advantage of this by keyframing the position.

thanks but i wonder, is it the same for PAL?

I doesn't matter what standard you use, just adjust the parameters for PAL resolution.

does anyone have an idea to what I should change it, when i use the numbers you say it works perfectly, but when I use the widescreen stuff for pal it won't