Online submission can be done through the Editiorial manager on the Springer website.
Information for authors can be found this page, which includes information on Manuscript Preparation Resources, further Explanation of the Journal Sections, Editorial Manager Instructions, Templates and File Formats, and Submitting Electronic Supplementary Information (see also below).
Regarding Electronic Supplementary Information (Data sets and computer code)
In the interest of transparency and reproducibility of results, Psychometika strongly encourages authors to include with published papers, where possible, electronic supplementary materials which will be published online on SpringerLink with the article. This includes data and code. Data and code should be clearly documented to allow replication and verification of the results presented in the final version of the paper. Authors should specify the type of supplementary material they will be able to provide at the time of submission, and this information will be taken into account in the review process.