Start with the right most column (highlighted).

1+1=10 (since we are using binary, so one bit is carried over to the next column.)

Add the highlighted column.

1+0+0=1, so there is no carry over. A carry over of zero is usually omitted.

Add the highlighted column.

Carry over 1 to the next column.

Add the highlighted column.

Carry over as necessary.

Add the highlighted column.

Add the highlighted column

Carry over the 1.

Add the highlighted column.

Carry over as necessary.

Add the highlighted column.

Carry over the 1.

The final sum.