You need a resource group, foundry resource, and foundry resource first.
Go to https://portal.azure.com and create a resource group.
Go to https://ai.azure.com/ and create a foundry project and select the resource group you created. This step will also automatically create a foundry resource.
When you’re on the foundry resource dashboard, click Models on the left side navigation and click Deploy > Deploy a base model or Deploy a fine-tuned model. On the page that follows, you can then search a model like gpt-5-mini. Click the selected model and click Deploy on its own page.