Hi Al,
Not sure what you mean by texting from your laptop. It depends on the service you intend to use. The sequence for texting to a foreign country is the same one used for dialing a phone call. In the case of Ukraine it is: 011 380 followed by a 9 digit cell number which may not begin with zero (if it does you should leave out the zero). You can also use +380 instead of 011380 when using a cell phone to call/text. More info at:
https://www.howtocallabroad.com/ukraine/
From the Ukraine to the USA: 00 1 xxx xxx xxxx or +1 xxx xxx xxxx. More info at:
https://www.howtocallabroad.com/results.php?callfrom=ukraine&callto=united_states
If you are using an online based VoIP service follow their instructions. Normally, the sequence should be the same, but they could for instance ask what country you are texting to and only require you to enter the local number (without 011 and 380).
I hope this helps.