You can create tension by setting up deadlines or time limits for the characters. Like, they have to complete a task before a certain time or something bad will happen.
One way to create tension is through character conflicts. When characters have opposing goals or motivations, it keeps readers on the edge of their seats wondering how it'll play out. Also, creating uncertainty about the outcome of events can heighten the tension.
One way to add tension is by creating time limits or deadlines for the characters. This makes the readers feel the urgency and keeps them on the edge of their seats.
You can start by creating a sense of uncertainty. Make readers wonder what's going to happen next. Also, build up to important events slowly to increase anticipation.
Create conflicts among the characters. Have them face difficult choices and high stakes. Also, introduce time pressure or limited resources to increase the tension.
To create tension in a horror story, start with a slow build-up of suspense. Use sound effects and descriptions of the environment to set the mood. And make the readers care about the characters so they worry about what might happen to them.