How can i connect two different pots parallel like a normal pot?
Voltage adjust
The schematic shows that. R9 is a 3-terminal pot with the wiper connected to one end. This makes it a variable resistor.



simulate this circuit &ndash; Schematic created using CircuitLab
Figure 1. Voltage coarse and fine.
If you want the fine adjustment control then add a 1k pot in series with R9 and with the wiper wired in the same configuration. The 10K part will then give you coarse control and the 1k pot will give you fine control.
Current adjust



simulate this circuit
Figure 2. Current coarse and fine.
Note that this adds an extra 1k into the R2 - R3 potential divider but if R2 is a 1% type it's resistance tolerance is ±2.2 kΩ.