How to update version 126.96.36.199 to version 5.7
I have to disappoint you. But at the moment there is no upgrade path for 5.6.* to 5.7.*.
There is 2 reasons for this:
1. The core of concrete5 5.7 is completely rebuild and therefore not compatible with earlier versions.
2. Any block, package and theme used in 5.6.*, also have to be converted to Concrete5 5.7.
We have converted Concrete5 Denmark website (www.concrete5.dk) to 5.7, and in that we had to make a new theme and move content manually from our old site to the new site. And we are not finished yet because of the fact that a lot of blocks/packages we used on the old site has not yet been converted to 5.7.
I know there is some groups of people here in the forum that is talking about making a tool to help migrating from 5.6 to 5.7, but I am sceptic, and I can't see how that would be done. Mostly because you would have to make some code that automatically converted themes and packages to its new code base with namespaces and everything. The only tool I could see was somkind of export and import of content, not converting a whole site.
The plus site should be that it is not that difficult to build pages in 5.7, it is actually kind of fast when you get the hang of it.