Integrate Buck Cobverter on PCB (EasyEda)

I want to make an custom PCB with EasyEda and my goal is to make an random power supply for my small projects that feeds my microcontrollers with power.

Input is going to be 5-19V DC and outputs going to be 5 and 9v that fits 3.3v and 5v boards.

But what is the recomended use of capasitors before and after buck converter that feeds my boards?

Input is going to be 5-19V DC and outputs going to be 5 and 9v that fits 3.3v and 5v boards.

I don't understand why you want 9V. Feed 5V with 5V into the 5V pin.

A power supply with a 'random' output does not sound very useful to me, maybe as a noise generator perhaps ?

But what is the recommended use of capacitors before and after buck converter that feeds my boards?

If you mean a ready made converter with all the components on a board then there should already be appropriately sized capacitors on the board. If you buy really cheap ones they might have skimped and used smaller capacitors that are ideal.

The best place to find out what the capacitors should be is from the data sheet of the chip on the board. In general higher value than specified capacitors are not a problem.

The requirements for external components of the buck converter (inductor, capacitors, and usually a diode, though some buck converter IC's integrate this, and potentially a MOSFET if the buck converter IC doesn't integrate that (most smaller ones do)) will be specified by the datasheet for the buck converter IC. Most of these also provide a recommended layout - switching DC-DC converters are notoriously sensitive to layout (and the specifics of external components).

A buck converter cannot produce 9v output from 5v.

For a 3.3v board, you should supply 3.3v

Why would you ever be supplying 9v?! The regulators on arduino boards are rarely fit for purpose...

Why are you making your own? Buck converters are fiddly to design (that layout sensitivity), and off-the-shelf DC-DC converters are readily available on ebay for less than us in the west can source the components for, let alone make a board and assemble it. Unless you have specific needs that are not met by available boards (what you've mentioned seems an easy spec to meet), I recommend using those - even I don't design my own buck/boost converters unless I need to (I have twice - once when I needed a very specific controller that had a very low minimum voltage and high current that we couldn't get in an off-the-shelf converter, and later for my ATtiny43 breakout board https://www.tindie.com/products/drazzy/attiny43-wintegrated-boost-arduino-compatible/. In both cases, I had problems with the initial version - in the first case, there was a complication I hadn't forseen relating to a minimum output voltage, and in the second, it was just bad component selection because I didn't internalize the warning in the datasheet about reverse leakage, so it was easy to fix, if a bit stressful because the problem was discovered AFTER I'd put them up for sale and someone had placed an order...) If the only issue is the connections having the required pinout or connector, pick a good module, and provide a spot to connect it (I use pin header soldered directly on both side, and the ends of the long side clipped off once it's soldered).

Bjerknez:
But what is the recomended use of capasitors before and after buck converter that feeds my boards?

The datasheet for the converter chip should provide full detail how to choose components for it, and
for pcb layout. Follow these to the letter, the type and value of every capacitor and inductor is crucial.

Its much easier not to do this and use an off-board DC-DC converter!

To integrate a buck converter into your custom PCB, you take the buck converter module, measure out the locations of the input positive and ground and the output positive and ground terminations, and plot them to your PCB so you can mount the converter module on suitable pins to connect it.