On top plane, insert a sketch as below sketch;
In this sketch you will dimension basic lines, angle and circle. Lets dimension lines first, click Smart Dimension 
and click bottom line
Click on middle line
and pull the dimension to left side.
Click on middle line
click on top line edge
pull the dimension to left side.
Click on bottom line edge
and pull the dimension down.
Click on middle line
and pull the dimension upward.
Click on top line edge
and pull the dimension upward.
Now let’s dimension angular sketch, click on right edge
click on angular line
and pull the dimension upward.
Now let’s dimension circle sketch, click on circle edge
and pull the dimension to right side.
For its position click on circle edge
click on right side edge
and pull down the dimension.
Click on circle edge,
click on bottom edge
and pull the dimension to right side.
You have finished your sketch! Well done.
