You can check your alignment at a basic level with chalk or crayon and a measuring tape.
First park the car on a flat surface with the steering in a straight line and then measure the distance between the inside edge of the front tires IN FRONT of the axle, and then measure the distance between the inside edge of the front tires BEHIND the axle.
With a little bit of toe-in which for most cars is typical you might measure about 1/8" to 1/4" toe-in, meaning the wheels are 1/8" closer in the front than in the rear of the axle. And you can do the same measurement for the back wheels, but they should generally be zero toe, exactly straight in line, very few cars will have any toe in the rear.
Another way of checking this which is more subjective but nearly as informative, and only works if your car has a similar or wider track in the rear than in the front, is to kneel in front of the car and move until your line of sight along the outside edge of the front tire you see the front and rear edges of the front tire line up, and then see how much of the rear tire is showing. Do the same thing on the other side.
It is also possible you have dynamic balance issues such as having lost a wheel weight. It is better to have a shop check this.