First, you need to have data in a specific format required for creating parallel corpora. See our documentation about setting up parallel corpora that provide you more details about the supported formats of parallel data for creating parallel corpora in Sketch Engine.
When you have your data in the required format, upload them to Sketch Engine and create the parallel corpus. In fact, Sketch Engine creates separated monolingual corpora for each language of your parallel data and aligns these corpora to each other. This allows you to use the parallel concordance as well as the other features available for monolingual corpora in the specific language, e.g. a standard concordance tool, wordlists, word sketches, etc.