You don't need to defrag SSDs as fragmentation doesn't exist on those, or at least it's not a performance hit.
Defrag <volume> | /C | /E <volumes> [/A | /X | /T] [/H] [/M] [/U] [/V] The options for Defrag.exe are: <volume> The drive letter or mount point of the volume to defragment. /C Defragment all local volumes on the computer. /E Defragment all local volumes on the computer except those specified. /A Display a fragmentation analysis report for the specified volume without defrag¬menting it. /X Perform free-space consolidation. Free-space consolidation is useful if you need to shrink a volume, and it can reduce fragmentation of future files. /T Track an operation already in progress on the specified volume. /H Run the operation at normal priority instead of the default low priority. Specify this option if a computer is not otherwise in use. /M Defragment multiple volumes simultaneously, in parallel. This is primarily useful for computers that can access multiple disks simultaneously, such as those using SCSI- or SATA-based disks rather than disks with an IDE interface. /U Print the progress of the operation on the screen. /V Verbose mode. Provides additional detail and statistics. Some Points To Remember: Disk Defragmenter does not defragment files in the Recycle Bin. It is best to run Disk Cleaner first and then empty the Recycle Bin, before defragmenting Disk Defragmenter will also not defragment files which are in use. Best to try and shut down as many processes as possible and then defragment. Disk Defragmenter does not defragment the following files: Bootsect DOS, Safeboot fs, Safeboot csv, Safeboot rsv, Hiberfil sys, Memory dmp and the Windows page file. However using the -b parameter will optimize the boot files.
Or just use a 3rd party program, like Defraggler. It even has boot time defrag to defrag your system files, pagefile etc.