What are the steps of splicing?

There are two primary steps involved in splicing. 

1. During the first step, the pre-mRNA is cut at the 5' splice site, separating the 5' exon from the intron. Then, the 5' end of the intron is connected to the branch point within the intron, forming a looped structure known as a lariat. 
2. In the second step, the 3' splice site is cut. The two exons are then joined together (ligation) and the intron is released, resulting in a mature mRNA molecule ready for translation.