When I try to build a build and get it to fetch from github I get this error

Started by user Iain
Building in workspace /var/lib/jenkins/workspace/BitzCommands
Checkout:BitzCommands / /var/lib/jenkins/workspace/BitzCommands - hudson.remoting.LocalChannel@55f9bcfa
Using strategy: Default
Cloning the remote Git repository
Cloning repository origin
Error trying to determine the git version: Error performing command: --version
Assuming 1.6
ERROR: Error cloning remote repo 'origin' : Could not clone git@github.com:PvM_Iain/BitzCommands.git
hudson.plugins.git.GitException: Could not clone git@github.com:PvM_Iain/BitzCommands.git
at hudson.plugins.git.GitAPI.clone(GitAPI.java:268)
at hudson.plugins.git.GitSCM$2.invoke(GitSCM.java:1122)
at hudson.plugins.git.GitSCM$2.invoke(GitSCM.java:1064)
at hudson.FilePath.act(FilePath.java:842)
at hudson.FilePath.act(FilePath.java:824)
at hudson.plugins.git.GitSCM.checkout(GitSCM.java:1064)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1256)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:589)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:88)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:494)
at hudson.model.Run.execute(Run.java:1502)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:236)
Caused by: hudson.plugins.git.GitException: Error performing command: clone -o origin git@github.com:PvM_Iain/BitzCommands.git /var/lib/jenkins/workspace/BitzCommands
at hudson.plugins.git.GitAPI.launchCommandIn(GitAPI.java:862)
at hudson.plugins.git.GitAPI.access$000(GitAPI.java:40)
at hudson.plugins.git.GitAPI$1.invoke(GitAPI.java:264)
at hudson.plugins.git.GitAPI$1.invoke(GitAPI.java:244)
at hudson.FilePath.act(FilePath.java:842)
at hudson.FilePath.act(FilePath.java:824)
at hudson.plugins.git.GitAPI.clone(GitAPI.java:244)
... 13 more
Caused by: java.lang.NullPointerException
at hudson.Launcher.printCommandLine(Launcher.java:592)
at hudson.Launcher.maskedPrintCommandLine(Launcher.java:614)
at hudson.Launcher$LocalLauncher.launch(Launcher.java:700)
at hudson.Launcher$ProcStarter.start(Launcher.java:338)
at hudson.Launcher$ProcStarter.join(Launcher.java:345)
at hudson.plugins.git.GitAPI.launchCommandIn(GitAPI.java:843)
... 19 more
Trying next repository
ERROR: Could not clone repository
FATAL: Could not clone
hudson.plugins.git.GitException: Could not clone
at hudson.plugins.git.GitSCM$2.invoke(GitSCM.java:1134)
at hudson.plugins.git.GitSCM$2.invoke(GitSCM.java:1064)
at hudson.FilePath.act(FilePath.java:842)
at hudson.FilePath.act(FilePath.java:824)
at hudson.plugins.git.GitSCM.checkout(GitSCM.java:1064)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1256)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:589)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:88)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:494)
at hudson.model.Run.execute(Run.java:1502)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:236)

I'm new to Jenkins and don't know to set it up properly.