What's it a drawing of? It's a big question, because TC gives you tools to design things in 3D in multiple ways. One paradigm is called Constructive Solid Geometry, CSG, which is assembling primitive shapes like blocks, cylinders/cones and spheres/ellipsoids. Then there's feature-based, where faces, vertexes and edges can have contextual actions performed on them; history-based, where "stacked" features can't exist independently, because they're a "child" of "parent" features that have to be created first. Then there's parametric modelling, in which features have relationships to each other that can be fixed or have variations established from tables or formulas. Giving 2D drawings depth is called "2.5D CAD" because it doesn't consider the relationship of a plan view to end views or elevations, only the object's footprint. You can set up the relationship of your drawings to correlate with those views, extruding and intersecting each of them begins to approach 3D, and then you're going to have to learn how to apply features like filleting, chamfering and shelling, how to use tools like Boolean interactions to add, subtract and intersect, how to manipulate objects to establish relationships, and much, much more. Reading the manual's a useful start if you don't know any of this.