<div class="textTextmenu">
      <img src="pic/postimage.png"/>
        <span>
         span 1
        </span>
        <span>
            span 2
       </span>
   </div>

.textTextmenu>img:first-child{
  border:2px solid red;
 /*How to select First child? / this way is wronge and image is not selected*/
}

.textTextmenu img:first-child{
  border:2px solid red;
 /*How to select First child? / this way is wronge and image is not selected*/
}

.textTextmenu img:first-child{
  border:2px solid red;
}

1)    .textTextmenu span:first-of-type { color:red }
2)    .textTextmenu :nth-child(1){border:1px solid red;}
3)    .textTextmenu span:nth-child(2){color:red;}

.textTextmenu img + span{
  border:2px solid red;
 /*How to select First child? / this way is wronge and image is not selected*/
}