This is an enterview , and client ask me to have a black band which is little see trough, on top of the image and at the bottom of the image, then on top of the band I write the questions that the person is answering,
How can i do such a thing? I am a bit unexperienced
There are several ways you could do this and Motion is probably the most flexible overall.
If you are not familiar with Motion (which is a great way to do this) you could do it in FCP. It will need a couple of video layers and a little fiddling and some rendering so may be time consuming depending on how much you have to do.
On a video layer above your pictures simply overlay some 'slug'
Then on the slug layer apply the effect 'Mask Shape' from the Matte option in the effects pallete. This by default will create a black square in the middle of your pictures.
Then select 'invert' and use the horitontal and vertical scale to get the correct amount of black bar top and bottom.
Then select the 'motion' tab and adjust the opacity so that it becomes as transparent as you need.
If you want your bars to be a colour rather than black then you can overlay a matte colour instead of slug. Otherwise do the same.
Then just add your captions to the video layer above.
As I said its a little fiddly and also will need rendering but you can just copy and paste it wherever you need it on your timeline and make it as long or as short as you like.
A much simpler way is to use the FCP lower 3rds text gen. It has a solid background and you can adjust color and opacity. You can crop the size using the crop adjustments in the motion tab and even feather the edges.
If you want a more sophisticated solid bar, the free Alex4D plugin version gives more control over the solids shape and gradient.