OSCOLA uses footnotes rather than in-text citations. Each note ends with a full stop, and the footnote marker goes after the punctuation at the end of the sentence or clause it supports.
Cite a case in full the first time, then use a short form afterwards. Always insert footnotes with your word processor's footnote tool rather than typing superscript numbers, so they renumber automatically as you edit.
Those are the mechanics. For the form each kind of source takes, see how to cite books, articles and websites in OSCOLA, and for what the 2026 edition altered, how to write OSCOLA references in the 5th edition.