Fast Travel menu has a nice local map display, which does help you with your travel orientation. You will be visiting this menu, no matter if you are using Fast Travel or not. Just for the sake of this map. You do not need to use Fast Travel, if you hit immediately "z-stop" key.
You could just "walk" and later even "jog" while using "sneak", which helps training your skills and abilities. However the random animal spawn algorithm translating the abstract world into the adventure playing world, could at rare occasions do something nasty, like bringing nasty lag in some location and/or hard crashes to desktop (0 weight weasel?). But then it can also happen anytime you exit Fast Travel too, so... Choices
To get to the surface, I would suggest you fast travel back or "walk/jog" to the dwarven fortress. Once there, try finding your way to the surface yet again. Symbol for stairs could be covered under some items on the floor. There are only few other paths, which lead also from underground to surface. They are far away and well between. Some can be found in monster's caves. Most monster sites are lairs not caves. Other passages to/from underworld are at goblins' Dark Fortresses ( how many depends how well gobbos do in this world ) and not advisable without fully skilled and trained adventurer. Plus 10000 trolls at Dark Fortresses will slow down to crawl even 4ghz I7 cpu. So, be warned. Most dwarven fortresses should have those passages to underground sealed though. Also, if you play on tiny world, try not to make too much impact on world, before getting to the surface. Walls inside of fortresses do shift from time to time, while losing inside of them and from the rest of the game some characters, which you are maybe later interested to meet. You could close yourself underground this way.