Writing a test class on a Trigger in Salesforce - unit-testing

Question

I am a complete code noob and need help writing a test class for a trigger in Salesforce. Any help would be greatly appreciated.
Here is the trigger:
trigger UpdateWonAccounts on Opportunity(before Update) {
Set < Id > accountIds = new Set < Id > ();
//Collect End user Ids which has won Opportunities
for (Opportunity o : Trigger.new) {
if (o.isWon && o.EndUserAccountName__c != null) {
accountIds.add(o.EndUserAccountName__c);
}
}
List < Account > lstAccount = new List < Account > ();
//Iterate and collect all the end user records
for (Account a : [Select Id, Status__c From Account where Id IN : accountIds]) {
lstAccount.add(new Account(Id = a.Id, Status__c = true));
}
//If there are any accounts then update the records
if (!lstAccount.isEmpty()) {
update lstAccount;
}
}

Answer 1

Read An Introduction to Apex Code Test Methods and How To Write A Trigger Test.
Basically, you want to create a new testmethod that updates (inserts, deletes, undeletes, etc. depending on your trigger conditions) a record or sObject.
It looks somewhat like this:
public class myClass {
static testMethod void myTest() {
// Add test method logic to insert and update a new Opportunity here
}
}