During meditation how do I focus What is the best way to focus? 

And also how can I stop passing judgment on myself during? Its really difficult.
To focus, you remember to keep the mind on the meditation object (breathing) &amp;, when the mind strays, just bring it back to the object. 

When the mind strays, it is not "you" that is intentionally straying but the mind itself therefore it is not logical to judge "yourself" since the mind is the problem rather than "yourself". 

If the mind is straying a lot and you are judging yourself a lot, you may have to train the mind new ways of acknowledging the straying, such as mentally noting: "The mind is straying"; "the mind has craving"; "the mind has anger"; "the mind is restless"; etc or simply: "straying"; "craving"; "anger"; "restlessness", etc. 

In this way, instead of judging "yourself" &amp; attributing blame upon "yourself" unnecessarily &amp; unwarrantedly, the mind is judged or the states of mind are judged. 

There are preliminary meditation techniques for beginners such as the popular Mahasi Sayadaw method that use this  kind of mental noting. You may check out these methods or, otherwise, read about how the Buddha dealt with his straying mind in the sutta on Two Kinds of Thinking.