SFP+ is a slot designed primerally for fiber optic transciver modules. It is also possible to directly connect two SFP+ devices using a "SFP+ Direct attatch" cable.
Unfortunately 10GBASE-T transcievers for SFP+ slots are not readilly available. I've seen one vendor that claims to offer them but no indication of price was given. Also the distance was limited to 30m due to power limitations.
There are also media converters available in seperate boxes with their own power supplied that can interconnect between 10GBASE-T and fiber or SFP+ DA but iirc the prices were eye-watering and it means a messy extra box.
If you already have the cabling and switches in place for 10GBASE-T then your best option is almost certainly to buy a different network card that supports 10GBASE-T (e.g the Intel x520-T2 seems to be the 10GBASE-T equivilent of your card).
If your switches have SFP+ ports available then you could use those to connect to your NIC over either a SFP+ direct attatch cable or a pair of transcivers and a fiber cable.