Adding images next to each other

I can’t add two or more images in a post next to each other, on the same line.
I tried different themes but it is the same thing.
I tried editing different codes in the html editor but still nothing.
All of the pics I add get added under or above the other pic, even if they are small,they get added in a column.

And I’m currently using the Piano Black 1.3 theme.

Please help.