All manuscripts undergo double-blind peer review, and the process usually takes two to three weeks. 

At least two independent external experts are invited to participate in the review.

The editor makes the final decision on the manuscript. He sends  it via email to the author (including any relevant comments by reviewer if any). If needed, the authors make all the necessary additions and improvements. After that another round of reviewing might be necessary.

When the paper is considered acceptable for publication, it is sent to production.