for this x < 3

would I put a dot on 3 (on the y-axis)

and it would be a dotted line just through 3 vertical.

and which side would be shaded the right side where the x-axis is negatives.

X < 3

Graph: x = 3 = The boundary line = a
vertical dotted line.

x = 3 for all values of y:
P1(3 , -2) , P2(3 , 2) , (3 , 4).

All points to the left of the dotted
line should satisfy the inequality,
but none of the points on the line
should satisfy the inequality.

If there was an = sign in your inequality, it would be a solid line
and all points on it would satisfy
the inequality.