here. enjoy

src/main/java/com/zipcodewilmington/danny_do_better_exercises/StringUtilities.java

      * @return the concatenation of two strings, `firstSegment`, and `secondSegment`
      */
     public static String concatenation(String firstSegment, String secondSegment){
-        return firstSegment.concat(secondSegment);
+        return firstSegment + secondSegment;
     }
 
     /**
      * @return the last 3 characters of `input`
      */
     public static String getSuffix(String input){
-        return input.substring(0,-3);
+        return input.substring(input.length()-3, input.length());
 
     }
 
      * @return the equivalence of two strings, `inputValue` and `comparableValue`
      */
     public static Boolean compareTwoStrings(String inputValue, String comparableValue){
-        return true;
+        return inputValue.equalsIgnoreCase(comparableValue);
     }
 
     /**
      * @return the middle character of `inputValue`
      */
     public static Character getMiddleCharacter(String inputValue){
-        return getMiddleCharacter(inputValue);
+        int length;
+        int position;
+        if (inputValue.length() % 2 ==0) {
+            position = inputValue.length()/2-1;
+            length = 2;
+
+        } else {
+            position = inputValue.length()/2;
+            length = 1;
+        }
+
+        return inputValue.charAt(position);
     }
 
     /**
      * @return the first sequence of characters
      */
     public static String getFirstWord(String spaceDelimitedString){
-        return getFirstWord(spaceDelimitedString);
+
+        String answer = "";
+
+        for (int i = 0; i< spaceDelimitedString.length(); i++){
+            if (spaceDelimitedString.charAt(i) == ' ') {
+                answer = spaceDelimitedString.substring(0, i);
+            }
+        }
+        return answer;
     }
 
     /**
      * @return the second word of a string delimited by spaces.
      */
     public static String getSecondWord(String spaceDelimitedString){
-        return getSecondWord(spaceDelimitedString);
+
+        String[] answer = spaceDelimitedString.split(" ");
+
+        return answer[1];
     }
 
+
+
     /**
      * @param stringToReverse
      * @return an identical string with characters in reverse order.
      */
     public static String reverseTheTwo(String stringToReverse){
-        return reverseTheTwo(stringToReverse);
+        String answer = "";
+
+        for (int i = stringToReverse.length()-1; i >= 0; i--) {
+            answer = answer + stringToReverse.charAt(i);
+        }
+
+        return answer;
     }
 }

src/test/java/com/zipcodewilmington/danny_do_better_exercises/TestStringUtilities.java

     public void substringBeginTest(){
         // : Given
         String input = "Hello";
-        String expected = "olleH";
+        String expected = "Hel";
 
         // : When
         String actual = StringUtilities.getPrefix(input);
         String expected = "Wilmington";
 
         // : When
-        String actual = StringUtilities.getFirstWord(input);
+        String actual = StringUtilities.getSecondWord(input);
 
         // : Then
         assertEquals(expected, actual);