Hello ,
The below KB article link covers complete steps for upgrading from QC 10.0 to ALM 11.5 :
http://support.openview.hp.com/selfsolve/document/KM00474177
It has links to other necessary KB articles , link to "Upgrade best practices" guide.
The KB can be used for all details.
Coming to your environment where DB has to be migrated from Oracle to SQL , there is extra work which needs to be done.
You have to install and configure a SQL DB at your QC 10.0 end . Make a copy of each of the project in QC 10.0 and store the copies in the new SQL DB.
This SQL DB backups of QC 10.0 can be restored in your ALM 11.5 SQL DB. Or the same SQL server ( used for QC 10.0 ) can be used for ALM 11.5.
So you need to do this copying process 1st , then you can refer the KB article for steps on upgrade.
*One best practise is that always keep of backup of things so that it can be restored when things go wrong.
Regards,