You would type it like this (except remove the spaces).
< img src="the URL of the picture" >
The URL is the address of the picture you want to post, like the one below.
All of the above would go between the quotation marks. To put multiple pics in one post just repeat the second line. < img src=" " >
Your final line to post pics would look like this (again, remove the spaces)
< img src="https://www.carmodelingcorner.com/images/AMT_Models/AMT_1963_Chevrolet_Impala_SS_New/AMT_1963_Chevrolet_Impala_SS_D_01.jpg" >
Hope this helps.